Medical procedures involving the delivery or removal of fluids from the body often utilize a catheter system for fluid transport. The catheter system may include a flexible tube or catheter that operatively enters the body, and an externally located fluid reservoir. One example of a removal catheter system is a urinary catheter for use with patients that may have difficulty urinating.
Other catheter systems are capable of delivering a fluid, e.g., a therapeutic agent, to the body. For example, the use of intracerebroventricular or parenchymal catheters is known for infusing therapeutic agents to a specific location within the brain to treat a variety of disorders including, for example, chronic pain and movement disorders. In an illustrative example, an incision is made in a patient's scalp to expose the skull through which a burr hole may then be formed. The catheter may then be inserted through the burr hole and anchored in place, e.g., with a burr hole anchor. Surgeons may often use stereotactic apparatus/procedures to position catheters and other brain instruments (e.g., electrical stimulation leads). For example, U.S. Pat. No. 4,350,159 to Gouda illustrates an exemplary stereotactic instrument used to position an electrode.
As one can appreciate, once an inserted device such as a catheter is properly positioned, it is important that it be adequately immobilized to prevent movement from its intended location. Even minimal movement of the device tip may yield unsatisfactory therapeutic results. Accordingly, reliable methods and apparatus for anchoring and securing the device relative to the burr hole are needed. To secure the catheter relative to the burr hole, burr hole anchor devices, including devices similar to those described in U.S. Pat. No. 4,328,813 to Ray and U.S. Pat. No. 5,927,277 to Baudino et al., may be used.
Many of these anchor devices are used primarily to secure a catheter or lead for long term implantation. Some therapies (e.g., acute gene therapy for the treatment of Parkinson's disease, chemotherapy), however, may be delivered during a more limited period of time, e.g., a few hours to a few days or less. In the case of the latter, it may be beneficial to completely remove the delivery catheter at therapy completion. Device (e.g., catheter) removal, though, generally requires a surgical procedure to: expose the burr hole and anchor; release the catheter from the anchor; remove the catheter; and close the incision. While effective, such a removal procedure may be undesirable for various reasons, including, for example, cost and potential patient apprehension associated with the surgical removal procedure.
The portion of the catheter extending beyond the skull may be tunneled beneath the skin (e.g., to connect to an implanted reservoir or pump) or, alternatively, routed outside the body where it may connect, typically via a longer secondary tube, to an external source containing the therapeutic agent.
While fully implanted systems may be beneficial for long term treatment of certain chronic ailments, external routing may be preferable for shorter term therapies (e.g., those lasting a few days or less). Current external routing configurations may, however, present issues not necessarily present with internal systems. For example, the externalized components may benefit from various attachment and strain relief techniques to minimize movement of the implanted catheter that might result from exposure to inadvertent, external forces. Moreover, in the event of a catheter break, the externalized catheter system may require component replacement and/or additional sterilization procedures in order to reduce potential contamination. While such attachment techniques and sterilization procedures are effective, it may be beneficial if the need for such additional measures could be reduced or eliminated.
Short term therapies may further benefit from catheters that are of an advantageous size (e.g., diameter) for the particular therapy delivery profile. For example, many conventional catheters are of a diameter that is unnecessarily large for shorter term, low volume therapy delivery. However, conventional catheters having a small diameter may be subject to inadvertent occlusion as a result of anchoring or twisting of the catheter.